1. Field of the Invention
The present invention relates to a cutting apparatus for corrugated cardboard sheets for slitting a corrugated cardboard sheet along the traveling direction of the sheet.
2. Description of the Prior Art
FIG. 6 to FIG. 8 are figures for explaining the construction and function of a cutting apparatus for corrugated cardboard sheets in the prior art, which show a die cutter portion of a corrugated cardboard processing machine as an example. In addition, FIG. 9 is an illustrative figure of construction of a general corrugated cardboard processing machine, and FIG. 10 is a figure for explaining processing states of a corrugated cardboard sheet which corresponds to the processing machine in FIG. 9 with respect to upper and lower positions.
At first, the die cut portion, which is installed in the corrugated cardboard processing machine shown in FIG. 9, has a mechanism for performing die cutting processing to obtain a predetermined product shape with respect to a corrugated cardboard sheet 5 conveyed from a paper supply portion 17 one by one to pass through one set or plural sets of printing portions 18a and 18b to be subjected to predetermined printing, which is such a portion in which die cutting and separation are performed at once to obtain plural sheets of product sheets 19 from one sheet of the corrugated cardboard sheet 5 in the widthwise direction of the machine as 2 sheets or 3 sheets (as called two takes or three takes).
As exemplified in FIG. 6 to FIG. 8, a sheet cutting portion in the above-mentioned die cut portion is constituted by a knife cylinder 2 to which a knife 4 is secured at the outer circumferential surface via a knife mounting stand 3 and an anvil cylinder 1, and by means of pinching and opposing rotation of the knife 4 of the same knife cylinder 2 and the anvil cylinder 1, the corrugated cardboard sheet 5, which travels between the both cylinders 1 and 2 with being pinched and conveyed by sending rolls 21a and 21b, is cut.
In the cutting apparatus for corrugated cardboard sheets in the prior art shown in the above-mentioned FIG. 6 to FIG. 8, in order to carry the process between the contact of the knife 4 with the traveling sheet 5 and the completion of cutting in one step, there have been several disadvantages. For example, in the case of a composite paper sheet such as the thick corrugated cardboard sheet 5 comprising core paper (center core) 15 and liners 14 and 16 or the like, the sudden force action accompanied by the pressurized pinching of the knife causes the cut portion to be crushed, and the liner 16 is suddenly pulled by compression, resulting in occurrence of breaks at the liner portion closely adjacent to an engaging portion of the knife 4. Also, cracks generally called footprints of a crow and the like are created.